Controller.



No. 858,399 PATENTED JULY 2, 1907. M. KELLY.

CONTROLLER.

APPLIOATION FILED SEPT. 22A 1906.

3 SHEETSf'BHEET 1.

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No. 858,399. PATENTED JULY 2, 1907.

' M. KELLY.

CONTROLLER.

APPLICATION IILED SEPT. 22, 1906.

3 SHEETS-SHEET 2.

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PATENTED JULY 2, 1907.

M. KELLY.

CONTROLLER.

APPLIOATION FILED 811F122, 1906.

3 SHEETS-SHEET 3.

UNITED STATES PATENT OFFICE.

MICHAEL KELLY, OF HAMMOND, INDIANA, ASSIGNOR TO FRANK S. BETZ, OF CHICAGO, ILLINOIS.

CONTROLLER.

Specification of Letters Patent.

Patented July 2, 1907.

Application filed September 22,1906. Serial No- 335,710.

To all whom it may concern:

Be it known that I, MIeHAEL KELLY, a citizen of the United States of America, and a resident of Hammond, in the county of Lake and State of Indiana, have invented certain new and useful Improvements in Controllers, of which the following is a specification.

The main objects of this invention are to provide an improved form of controller for dental motors, adapted to rest upon the floor and be operated by the foot of an operator while the same foot is resting upon the floor; to provide an improved structure wherein the contacts are inclosed and wherein the protecting casing is free from openings which tend to collect dust; and to provide an improved form of spring mechanism for controlling the relative movement of the controller member with respect to the resistance contacts and normally urging said controller member to its off position. These objects are accomplished by the device shown in the accompanying drawings, in which:

Figure 1 is a side elevation of a controller constructed according to this invention for use in connection with electrical dental engines operated by alternating current. Fig. 2 is a vertical section on the line 2-2 of Fig. I. Fig. 3 is a bottom plan of the casing removed from the base plate and showing the arrangement of the contact brushes. Fig. 4 is a top plan of the controller with the casing removed, the electrical connections being indicated diagrammatically. Fig. 5 is a detail in perspective of the support which carries the casing. Fig. 6 is a detail in perspective of the base plate. Fig. 7 is a detail of the spring mechanism which urges the casing toward a certain normal position with respect to the base and which yieldingly resists rotation of the casing in either direction from such normal position.

The example of this invention which is shown in the drawings is a controller having its electrical connections arranged for controlling the speed of an induction motor of the particular type which is indicated diagrammatically in Fig. 4. In said figure, the armature is indicated by the circle 3 and the field coils are indicated at 4. In the particular form of motor shown, the

' field is bi-polar and the armature may be of any type suitable for induction motors as for instance the drum type in which the successive coils are connected in series with each other and their joints are connected to the individual bars of the commutator. In this type of motor a change in the position of the brushes causes a change in the speed and the motor may be controlled or reversed by shifting the brushes as is well known. Such shifting of the brushes however gives rise to excessive sparking and it is preferred to control the speed by introducing variable resistance in the armature circuit. For reversing the direction two sets of brushes designated 5 and 6 respectively are provided, each set being located in the best position for its particular di rection of rotation.

The controller is provided with a rhcostat plate 8 of insulating material upon which are mounted a set of contact members 9 and 10 for controlling the field or stator circuit and a second set of contact members for controlling the armature or rotor circuit. The armature circuit contacts are designated by the refer ence numerals 11 to 16 inclusive. The two leads of the field circuit are respectively connected to the contact members 9 and 10 and the circuit between said contact members is controlled by a pair of brushes or contact shoes 17 carried by the casing and insulated therefrom, but in electrical connection with each other. A second set of contact shoes 18 similarly mounted controls the armature circuit.

The brushes 5 are respectively connected with the outermost contact button 16 and with the contact member 13 by the conductors I9 and 20. The brushes 6 are connected with the contact members 11 and L1- by the conductors 21 and 22 respectively. The contact members l1 and are connected together by the conductor 23. The contact shoes 17 and 18 are arranged in radial alinement with each other and the spring mechanism which will be hereinafter described normally urges the casing to a position which will bring one of the contact shoes 17 upon the of button 24, thus cutting off all current from the motor. When the casing is shifted a short distance in either direction from the of posi tion so that the shoes 18 connect the contact members 12 and 15 while the shoes 1.7 connect the contact members 9 and 10, current will be admitted to the hold but the armature will not rotate since this position of the shoes 18 short-circuits one of the brushes 5 with the adjacent brush 6, causing conflicting forces in the armature which prevent the rotation thereof. When the shoes 18 are in contact with the contact buttons I l or 16, one set only of the brushes will be in circuit and the motor will run in a corresponding direction. The variable resistance indicated at 25 and 26 will regulate the speed of the armature, the greatest speed in either direction corresponding to the extreme positions of the shoes 18 away from the off position.

When the motor is running at full speed in one direction, the movement of the controller shoes toward the middle position gradually reduces the speed by throwing increasing amounts of resistance into circuit with the armature. As soon as the shoes 18 pass into contact with the plates 12 and 15, the adjacent brushes 5 and 6 are short-circuited and the armature is brought to a standstill since the induced currents in the armature oppose each other and prevent rotation. Upon the arrival of the shoes at their middle position, the current is cut out of the field. As the controller shoes are shifted Cir beyond the contact members 12 and 15 in the opposite direction, the other set of brushes will be brought into play and the motor will be driven in the reverse direction.

The controller consists of a heavy base plate 27 having uprights 28 at opposite sides thereof. A member 2 9 is secured across the top of the uprights 28 and carries a central upright post 30 and a pair of uprights 31 at opposite sides of the post. A boss 32 at the foot of the post 30 supports a plate 33 of insulating material upon which are mounted the contact members 9 to 16 of the rheostat. These contact members are connected to the motor by their respective conductors which are led out of the channel 34 in the base plate in the iorm of a cable, not shown in the drawings. An annular seat or track 35 is formed at the upper ends of the uprights 31 concentrically of the post 30. A circular disk 36 is mounted on said seat and is rotatable thereon. The shoes 17 and 18 are secured to the disk but are insulated therefrom and from each other. An inverted cup-shaped casing 37 is carried by the disk 36 and incloses all parts above the base so as to protect the same from dust. A pair of pedals or wings 38 extend radially outward from the sides of the casing 37 near its lower edge so as to be in convenient position for being pushed toward one side by the foot of the operator while the same foot is resting upon the floor. The casing is prevented from being lilted away from the base by means of a screw 39 which passes loosely through the middle of the top of the cas ing and is threaded into the post 30.

The casing 37 has an inwardly extending lug 40 at one side near the lower edge of its rim. A pair of crossed levers 41 are pivotally connected at 42 with the base plate 27. The pivot at 42 is preferably located at the axial center line of the casing. The arms 43 of the levers extend in parallel relation to each other and are bent upward at their ends to engage opposite sides of the lug 40. A stop 44 on the base limits the movement of the arms 43 toward each other and serves to center the casing 37 so as to bring the shoes 17 into their central position oi contact with the off button 24. The other arms of the levers 41 are normally drawn toward each other by a tension spring 45.

When the casing is shifted in either direction from its central position, the lug 40 causes the corresponding arm 43 to swing with the casing and as the arm 43 of the other lever is prevented from swinging by the stop 44, such movement oi the casing exerts a tension on the spring 45 which normally urges the casing back to its middle position.

What I claim as my invention and desire to secure by Letters Patent is:

1. A controller comprising a base, resistance coils and a series of contact members mounted on said base, a casing surrounding said resistance coils and contacts and being rotatably mounted on said base, a contact shoe carried by said casing and bearing on said contact members, all arranged to vary the resistance in an electric circuit through the rotation of said casing.

2. The combination of a base, variable resistance mounted thereon, a series of contact members connected with said resistance, a casing surrounding said resistance and contact members and mounted to rotate on said base, a contact shoe carried by said casing and movable along said contact members, and a spring adapted to urge said casing toward a certain initial position with respect to said base.

I). In a controller, the combination olf a base, an inverted cup-shaped casing, mounted above said base and rotatable thereon on.a vertical axis, contacts carried by said base and casing and arranged to vary the resistance in an electric circuit through the rotation oisaid casing, a pedal on said casing for rotating the same, a pair ol' intersecting levers pivoially mounted on a common vertical axis on said base. a spring acting between said levers and normally urging said levers toward each other, a stop on said base for limiting the movement of said levers toward each other, and a lug on said casing extending between the opposite arms oiI said levers, all arranged to resist the rotation 01' said casing in either direction and to normally urge the casing to a certain initial position and with respect to said base.

4. In a controller, the combination oi a weighted base, having thereon a plurality of uprights, resistance coils mounted on said base, a horizontally disposed rheostat plate located above said resistance, a disk supported by said uprights and arranged to rotate concentrically ot' the base, contacts on said rheostat plate and disk coaeting with each other and adapted to vary the resistance in an electric circuit through the rotation of said disk with respect to the base, and an inverted cup-shaped casing car ried by said disk and extending over and around said disk and resistance coils.

5. In a. controller, the combination of a weighted base, having thereon a plurality oi. uprights, resistance coils mounted on said base, a horizontally disposed rheostat plate located above said resistance, a disk supported by said uprights and arranged to rotate concentrically of the base, contacts on said rheostat plate and disk coacting with each other and adapted to vary the resistance in an electric circuit through the rotation of said disk with respect to the base, an inverted cup-shaped casing carried by said disk and extending over and around said disk and resistance coils, and spriig mechanism acting between said base and casing for normally urging said casing toward a certain initial position.

(3. A controller comprising a base, resistance coils mount ed 011 said base, a series of contacts located above said resistance coils, a casing rotatably mounted on said base and inclosing said coils and contacts, said casing having a shoe adapted to cooperate with said contacts, and a pedal 011 the periphery of said casing for oscillating it.

Signed at Chicago this 11 day 01. September 1900.

MICHAEL KELLY.

Witnesses E. A. RUMMLnn, L. A. Snrru. 

